Factors associated with rectal injury in spontaneous deliveries.

Rectal injury during childbirth is a complication with potentially debilitating long-term consequences. Several factors have been suggested as influencing the risk of rectal injury. Among these are parity, infant birth weight, and various procedures performed by the birth attendant, including episiotomy. Whether episiotomies protect against or provoke laceration of the rectal sphincter and rectal mucosa is particularly controversial. Logistic analysis was used in an observational study of 2706 spontaneous cephalic deliveries to determine the risk of rectal injury for each of six explanatory factors, simultaneously controlling for the other factors. The adjusted risk for rectal injury was significantly increased for midline episiotomy (8.9 versus no episiotomy), nulliparity (3.3 versus parous), delivery by a physician (2.4 versus midwife), fetal macrosomia (2.4 versus normal weight), and delivery in a delivery room (2.0 versus labor bed). Compared with the risk for whites, significantly increased risk was found for Hispanic (1.9), Filipino (3.7), and Chinese (2.9) women. The practice of prophylactic midline episiotomy is questioned, and suggestions are offered for the design of experimental studies to resolve the questions raised.